Investigation of Water Vapour Permeability and mechanical properties of edible gelatin films

The effect of glycerol and sorbitol on mechanical properties and water vapour permeability of three type gelatins was investigated. For this purpose, gelatin was extracted from Whitecheek Shark Skin. Addition of plasticizer to all three types of gelatins decreased WVP in the specimens containing glycerol and sorbitol, but when glycerol content increased from 0.2g/g gelatin and sorbitol content increased from 0.25g/g gelatin, WVP increased due to increase in chain mobility and enhancement of the void spaces between polymer chains. Elongation at break of films increased with increasing plasticizer levels except when glycerol content increased from 0.25 to 0.3g glycerol/g gelatin type C films. This could be attributed to increase of chain mobility film matrix. Also with increasing of glycerol content of films observed a decrease of tensile strength and elastic modulus at all samples. Addition of sorbitol to gelatins type A and C films led to decrease of TS and EM contentiously except gelatin type B films that shown clearly decrease in concentration of 0.1g sorbitol/g gelatin and a constant value of TS up to 0.3g sorbitol/g gelatin and constant value of EM up to 0.25g sorbitol/g gelatin type B films, then an increase in EM value observed in concentration of 0.3g sorbitol/g gelatin. To achieve optimum edible films for food packaging, production and composition of fish skin gelatin films containing a mixture of glycerol and sorbitol plasticizer is recommended.

Keywords:

edible gelatin films , plasticizer , glycerol , sorbitol , mechanical properties , water vapour permeability